1. Field of the Invention
The present invention relates to a cylinder liner and a method of manufacturing the cylinder liner.
2. Description of Related Art
In general, cylinders are hollow cylindrical parts in which pistons are guided to reciprocate in internal combustion engines for vehicles. Other than the cylinders used in reciprocating piston internal combustion engines, typical cylinders are cylinders used in reciprocating compressors and cylinders used in oil pressure, hydraulic, and pneumatic machines.
In the reciprocating piston internal combustion engine, an engine equipped with one cylinder is called a single-cylinder engine.
Further, multi-cylinder engines are classified into an in-line type engine, a V-type engine, an opposed engine, and a radial engine, in accordance with the arrangement type of cylinders.
In the multi-cylinder engines, there is an engine having an integral structure by casting several cylinder parts into one block, which is called a cylinder block.
A part that is a relatively thin cylindrical tube that is inserted to provide a reciprocation surface for a piston reciprocating therein, when the guide reciprocation surface for the piston formed by directly machining above structure is insufficient in strength and durability is called a cylinder liner.
A predetermined number of cylinder liners are arranged in a mold in accordance with the displacement of an engine and then integrally formed with the cylinder block by pouring molten metal of a block material, by integral casting.
In this configuration, the gap between a pair of adjacent cylinder liner in the plurality of cylinder liners arranged in the cylinder block is called a bore gap.
In recent years, various efforts for reducing the size and weight of an engine by reducing as much as possible the bore gap between cylinder liners while increasing the bonding strength between the cylinder liners and a cylinder block have been made.
For example, a cylinder liner in the related art is schematically described below.
As shown in FIG. 1, according to a cylinder liner in the related art, grooves are formed on the surface of an coating material particularly in the process of applying the coating material to a mold in the manufacturing process, molten metal for a cylinder liner is poured into the surface of the coating material, the poured molten metal covers the surface of the coating material and permeates the grooves, and the molten metal is solidified after a predetermined time, and as a result, a parent body of the cylinder liner is completed.
Thereafter, the parent body of the cylinder liner is drawn out of the mold and the coating material on the outer surface is removed, such that a cylinder liner 5 having predetermined protrusions 5a throughout the outer surface is completed.
Consequently, a cylinder block integrally formed with the cylinder liner is completed by pouring again cylinder liner 5 in a mold for manufacturing a cylinder block and pouring molten metal of a block material, into the mold by integral casting.
Cylinder liners 5 integrally formed with the cylinder block are strongly combined with the cylinder block by protrusions 5a on the outer surfaces.
However, according to the cylinder liner in the related art, the cylinder liner can be strongly combined with a cylinder block by protrusions formed on the outer surface, whereas the cylinder liner is thick and the size of a bore gap correspondingly increases, such that there is a problem that the size and weight of an engine increase.
Further, the protrusions on the outer surface of the cylinder lines interferes with the flow of the molten metal of a block material that is inserted in the mold, such that there is a problem that the time for manufacturing the cylinder block increases with the decrease of the overall fluidity of the block material and inferior quality may be caused by long-time solidification.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.